Environmental exposure to cadmium impairs fetal growth and placental angiogenesis via GCN-2-mediated mitochondrial stress

Exposure to iodine, essential and non-essential trace element through seaweed consumption in humans

Seaweed consumption has gained popularity due to its nutritional value and potential health benefits. However, concerns regarding the bioaccumulation of several trace elements highlight the need for comprehensive studies on exposure associated with seaweed consumption. To address this gap in knowledge, we carried out a feeding intervention study of three common edible seaweeds (Nori, Kombu, and Wakame) in 11 volunteers, aiming to elucidate the extent of both beneficial and harmful trace element exposure through seaweed consumption in humans. Concentrations of total arsenic, cobalt, copper, cadmium, iodine, molybdenum, selenium, and zinc were measured in urine samples before and following seaweed consumption. Elements concentrations were also measured in the seaweeds provided for the study. Descriptive analysis for each element were conducted and we used quantile g-computation approach to assess the association between the 8-element mixture and seaweed consumption. Differences in urine element concentrations and seaweed consumption were analyzed using generalized estimating equations (GEE). Urinary concentrations of iodine and total arsenic increased after seaweed consumption. When we analyze the 8-element mixture, the largest weight was observed for iodine after Kombu consumption while for total arsenic was observed after Wakame consumption. Similar results were observed when we compared the mean differences between the elements before and after seaweed consumption through the GEE. Seaweed consumption relates with increased urinary iodine and total arsenic concentrations, particularly after Kombu and Wakame consumption.

NBR1-dependent autophagy activation protects against environmental cadmium-evoked placental trophoblast senescence

Cadmium (Cd), a well-established developmental toxicant, accumulates in the placentae and disrupts its structure and function. Population study found adverse pregnancy outcomes caused by environmental Cd exposure associated with cell senescence. However, the role of autophagy activation in Cd-induced placental cell senescence and its reciprocal mechanisms are unknown. In this study, we employed animal experiments, cell culture, and case-control study to investigate the above mentioned. We have demonstrated that exposure to Cd during gestation induces placental senescence and activates autophagy. Pharmacological and genetic interventions further exacerbated placental senescence induced by Cd through the suppression of autophagy. Conversely, activation of autophagy ameliorated Cd-induced placental senescence. Knockdown of NBR1 exacerbated senescence in human placental trophoblast cells. Further investigations revealed that NBR1 facilitated the degradation of p21 via LC3B. Our case-control study has demonstrated a positive correlation between placental senescence and autophagy activation in all-cause fetal growth restriction (FGR). These findings offer a novel perspective for mitigating placental aging and placental-origin developmental diseases induced by environmental toxicants.

An integrative data-centric approach to derivation and characterization of an adverse outcome pathway network for cadmium-induced toxicity

Cadmium is a prominent toxic heavy metal that contaminates both terrestrial and aquatic environments. Owing to its high biological half-life and low excretion rates, cadmium causes a variety of adverse biological outcomes. Adverse outcome pathway (AOP) networks were envisioned to systematically capture toxicological information to enable risk assessment and chemical regulation. Here, we leveraged AOP-Wiki and integrated heterogeneous data from four other exposome-relevant resources to build the first AOP network relevant for inorganic cadmium-induced toxicity. From AOP-Wiki, we filtered 309 high confidence AOPs, identified 312 key events (KEs) associated with inorganic cadmium from five exposome-relevant databases using a data-centric approach, and thereafter, curated 30 cadmium relevant AOPs (cadmium-AOPs). By constructing the undirected AOP network, we identified a large connected component of 18 cadmium-AOPs. Further, we analyzed the directed network of 59 KEs and 82 key event relationships (KERs) in the largest component using graph-theoretic approaches. Subsequently, we mined published literature using artificial intelligence-based tools to provide auxiliary evidence of cadmium association for all KEs in the largest component. Finally, we performed case studies to verify the rationality of cadmium-induced toxicity in humans and aquatic species. Overall, cadmium-AOP network constructed in this study will aid ongoing research in systems toxicology and chemical exposome.

Association between Mediterranean diet and metal mixtures concentrations in pregnant people from the New Hampshire Birth Cohort Study

Diet is a primary source of nutrients but also toxic metal exposure. In pregnancy, balancing essential metal exposure while reducing non-essential ones is vital for fetal and maternal health. However, the effect of metal mixtures from diets like the Mediterranean, known for health benefits, remains unclear. This study aimed to explore the association between Mediterranean diet adherence and metals exposure, both individually and as mixtures. The study involved 907 pregnant participants from the New Hampshire Birth Cohort Study. We calculated the relative Mediterranean diet score (rMED) through a validated food frequency questionnaire, which includes 8 traditional Mediterranean dietary components. Also, at ~24-28 weeks of gestation, we used ICP-MS to measure speciation of Al, Cd, Co, Cu, Fe, Hg, Mo, Ni, Sb, Se, Sn, Zn, and As in urine, as well as Pb, Hg, As, Ni, and Se in toenails. We used multiple linear regression and Weighted Quantile Sum regression to analyze the association between rMED and metal mixtures. The models were adjusted for age, pre-pregnancy BMI, smoking during pregnancy, and educational level. High adherence to the Mediterranean diet was associated with increased urinary Al (® = 0.26 (95 % confidence interval (CI) = 0.05; 0.46)), Cd (β = 0.12 (95%CI = 0.00; 0.24)), Mo (β = 0.10 (95%CI = 0.00; 0.20)), and AsB (β = 0.88 (95%CI = 0.49; 1.27)) as well as toenail Hg (β = 0.44 (95%CI = 0.22; 0.65)), Ni (β = 0.37 (95%CI = 0.06; 0.67)), and Pb (β = 0.22 (95%CI = 0.03; 0.40)) compared to those with low adherence. The intake of fruits and nuts, fish and seafood, legumes, cereals, meat, and olive oil were found to be related to the metal biomarkers within the rMED. In conclusion, the Mediterranean diet enhances essential metal intake but may also increase exposure to harmful ones.

Long-term exposure to cadmium disrupts neurodevelopment in mature cerebral organoids

Cadmium (Cd) is a pervasive environmental pollutant. Increasing evidence suggests that Cd exposure during pregnancy can induce adverse neurodevelopmental outcomes. However, due to the limitations of neural cell and animal models, it is challenging to study the developmental neurotoxicity and underlying toxicity mechanism of long-term exposure to environmental pollutants during human brain development. In this study, chronic Cd exposure was performed in human mature cerebral organoids for 49 or 77 days. Our study found that prolonged exposure to Cd resulted in the inhibition of cerebral organoid growth and the disruption of neural differentiation and cortical layer organization. These potential consequences of chronic Cd exposure may include impaired GFAP expression, a reduction in SOX2+ neuronal progenitor cells, an increase in TUJ1+ immature neurons, as well as an initial increase and a subsequent decrease in both TBR2+ intermediate progenitors and CTIP2+ deep layer cortical neurons. Transcriptomic analyses revealed that long-term exposure to Cd disrupted zinc and copper ion homeostasis through excessive synthesis of metallothionein and disturbed synaptogenesis, as evidenced by inhibited postsynaptic protein. Our study employed mature cerebral organoids to evaluate the developmental neurotoxicity induced by long-term Cd exposure.

Multigenerational paternal obesity enhances the susceptibility to male subfertility in offspring via Wt1 N6-methyladenosine modification

There is strong evidence that obesity is a risk factor for poor semen quality. However, the effects of multigenerational paternal obesity on the susceptibility to cadmium (a reproductive toxicant)-induced spermatogenesis disorders in offspring remain unknown. Here, we show that, in mice, spermatogenesis and retinoic acid levels become progressively lower as the number of generations exposed to a high-fat diet increase. Furthermore, exposing several generations of mice to a high fat diet results in a decrease in the expression of Wt1, a transcription factor upstream of the enzymes that synthesize retinoic acid. These effects can be rescued by injecting adeno-associated virus 9-Wt1 into the mouse testes of the offspring. Additionally, multigenerational paternal high-fat diet progressively increases METTL3 and Wt1 N6-methyladenosine levels in the testes of offspring mice. Mechanistically, treating the fathers with STM2457, a METTL3 inhibitor, restores obesity-reduced sperm count, and decreases Wt1 N6-methyladenosine level in the mouse testes of the offspring. A case-controlled study shows that human donors who are overweight or obese exhibit elevated N6-methyladenosine levels in sperm and decreased sperm concentration. Collectively, these results indicate that multigenerational paternal obesity enhances the susceptibility of the offspring to spermatogenesis disorders by increasing METTL3-mediated Wt1 N6-methyladenosine modification.

Fetoplacental Disposition and Toxicity of Cadmium in Mice Lacking the Bcrp Transporter

The environmental toxicant cadmium (Cd) impairs the growth of rodents and humans in utero which in turn heightens susceptibility to diseases later in life. We previously demonstrated that the maternal-facing efflux transporter, breast cancer resistance protein (human BCRP/ABCG2, mouse Bcrp/Abcg2) confers resistance against Cd toxicity in human trophoblasts. In the current study, we sought to determine whether the absence of Bcrp alters the fetoplacental disposition and toxicity of Cd in mice. Pregnant female wild-type (WT) and Bcrp-null mice (n = 9-10/group) were administered a single injection of saline (5 ml/kg) or CdCl2 (5 mg/kg) on gestational day (GD) 9. Following Cd treatment, Bcrp-null offspring were shorter and accumulated more Cd in their placentas on GD 17 compared to WT mice. Because Cd can adversely impact placentation and transplacental nutrient delivery in mice, multiple pathways were assessed using morphometrics and immunohistochemistry including placenta zonation, vasculature development, and nutrient transporter expression. Most notably, the placentas of Bcrp-null mice had reduced immunostaining of the cell adhesion marker, β-catenin, and the trophoblast marker, cytokeratin, as well as decreased expression of divalent metal nutrient transporters (Dmt1, Zip14, and ZnT1) following Cd treatment. In summary, the absence of Bcrp expression increased placental concentrations of Cd which was associated with shorter fetal size that may be related to differential changes in molecular patterns of placental development and nutrition.

Like father, like daughter:Paternal cadmium exposure causes hepatic glucose metabolic disorder and phospholipids accumulation in adult female offspring

Cadmium (Cd), is a well-known reproductive toxicant. The impacts of paternal Cd exposure on offspring glucose and lipid metabolism remain unclear, despite the abundance of adverse reports following early exposure from the mother. Here, we assessed paternally acquired metabolic derailment using a mouse model. LC-MS/MS, transcriptomics and molecular experimental techniques were subsequently applied in this study to explore the potential mechanism. We found that paternal Cd exposure caused glucose intolerance, lower insulin sensitivity and abnormal hepatic glycogen storage in adult female offspring, but not in males. LC-MS/MS data showed that hepatic phospholipids accumulation was also only observed in adult female offspring after paternal Cd exposure. Gene expression data showed that the level of insulin signaling and lipid transport-related genes was decreased in Cd-treated adult female offspring livers. Meanwhile, AHR, a transcription factor that combines with phospholipids to promote insulin resistance, was increased in Cd-treated adult female offspring livers. In addition, the escalation of the afore-mentioned lipid metabolites in the liver occurred as early as fetal stages in the female pups following paternal Cd exposure, suggesting the potential for these lipid species to be selected as early markers of disease for metabolic derailment later in life. Altogether, paternal Cd exposure causes offspring glucose metabolism disorder and phospholipids accumulation in a sex-dependent manner. This study provides a theoretical framework for future understanding of paternal-originated metabolic diseases.

Placental DNA methylation analysis of selective fetal growth restriction in monochorionic twins reveals aberrant methylated CYP11A1 gene for fetal growth restriction

Fetal growth restriction (FGR) is associated with increased susceptibility to perinatal morbidity and mortality. Evidence suggests that epigenetic changes play critical roles in the regulation of fetal growth. We sought to present a comprehensive analysis of the associations between placental DNA methylation and selective fetal growth restriction (sFGR), which is a severe complication of monochorionic twin pregnancies, characterized by one fetus experiencing restricted growth. Genome-wide methylation analysis was performed on 24 placental samples obtained from 12 monochorionic twins with sFGR (Cohort 1) using Illumina Infinium MethylationEPIC BeadChip. Integrative analysis of our EPIC data and two previous placental methylation studies of sFGR (a total of 30 placental samples from 15 sFGR twins) was used to identify convincing differential promoter methylation. Validation analysis was performed on the placentas from 15 sFGR twins (30 placental samples), 15 FGR singletons, and 14 control singletons (Cohort 2) using pyrosequencing, quantitative real-time polymerase chain reaction, western blot, and immunohistochemistry (IHC). A globe shift toward hypomethylation was identified in the placentas of growth-restricted fetuses compared with the placentas of normal fetuses in monochorionic twins, including 5625 hypomethylated CpGs and 452 hypermethylated CpGs, especially in the regions of CpG islands, gene-body and promoters. The analysis of pathways revealed dysregulation primarily in steroid hormone biosynthesis, metabolism, cell adhesion, signaling transduction, and immune response. Integrative analysis revealed a differentially methylated promoter region in the CYP11A1 gene, encoding a rate-limiting enzyme of steroidogenesis converting cholesterol to pregnenolone. The CYP11A1 gene was validated to have hypomethylation and higher mRNA expression in sFGR twins and FGR singletons. In conclusion, our findings suggested that the changes in placental DNA methylation pattern in sFGR may have functional implications for differentially methylated genes and regulatory regions. The study provides reliable evidence for identifying abnormally methylated CYP11A1 gene in the placenta of sFGR.

Placental BCRP transporter reduces cadmium accumulation and toxicity in immortalized human trophoblasts

Cadmium (Cd) is a ubiquitous environmental metal detectable in most pregnant women. Animal and human studies demonstrate that in utero exposure to Cd reduces birth weight and impairs perinatal growth due to placental toxicity. BCRP is a prominent transporter that can efflux xenobiotics from the placenta. This study sought to investigate Cd transport and toxicity in cultured human BeWo trophoblasts with reduced expression and function of the placental barrier transporter BCRP. Knockdown (KD) of BCRP protein expression and function in BeWo trophoblasts increased the intracellular accumulation of Cd by 100% following treatment with 1 μM CdCl2. No change in the expression of Cd uptake transporters was observed between control and BCRP-KD cells. Reduced BCRP expression impaired viability of BeWo cells exposed to CdCl2 for 48 hr (BCRP-KD IC50: 11 μM, control cells IC50: 18 μM). Moreover, BCRP-KD cells were more sensitive to CdCl2-induced cytotoxicity compared to control BeWo cells. CdCl2 treatment strongly induced the expression of the metal-binding protein metallothionein (MT) in both control and BCRP-KD cells, with significantly greater MT upregulation in Cd-treated BCRP-KD cells. These data suggest that the BCRP transporter reduces Cd accumulation in syncytiotrophoblasts, which may be one mechanism to reduce subsequent toxicity to the placenta and developing fetus.

Transition metals in angiogenesis - A narrative review

The aim of this paper is to offer a narrative review of the literature regarding the influence of transition metals on angiogenesis, excluding lanthanides and actinides. To our knowledge there are not any reviews up to date offering such a summary, which inclined us to write this paper. Angiogenesis describes the process of blood vessel formation, which is an essential requirement for human growth and development. When the complex interplay between pro- and antiangiogenic mediators falls out of balance, angiogenesis can quickly become harmful. As it is so fundamental, both its inhibition and enhancement take part in various diseases, making it a target for therapeutic treatments. Current methods come with limitations, therefore, novel agents are constantly being researched, with metal agents offering promising results. Various transition metals have already been investigated in-depth, with studies indicating both pro- and antiangiogenic properties, respectively. The transition metals are being applied in various formulations, such as nanoparticles, complexes, or scaffold materials. Albeit the increasing attention this field is receiving, there remain many unanswered questions, mostly regarding the molecular mechanisms behind the observed effects. Notably, approximately half of all the transition metals have not yet been investigated regarding potential angiogenic effects. Considering the promising results which have already been established, it should be of great interest to begin investigating the remaining elements whilst also further analyzing the established effects.

Cadmium reduces growth of male fetuses by impairing development of the placental vasculature and reducing expression of nutrient transporters

In utero exposure to the toxic metal cadmium (Cd) alters fetoplacental growth in rodents and has been inversely associated with birth weight and infant size in some birth cohorts. Moreover, studies suggest that Cd may have differential effects on growth and development according to offspring sex. The purpose of the current study was to evaluate changes in male and female fetoplacental development following a single injection of saline (5 ml/kg ip) or cadmium chloride (CdCl2, 2.5, 5 mg/kg, ip) on gestational day (GD) 9. By GD18, no changes in fetal or placental weights were observed after treatment with 2.5 mg/kg CdCl2. By comparison, the weight and length of male fetuses and their placentas were reduced following treatment with 5 mg/kg CdCl2 whereas no change was observed in females. In addition, the area of maternal and fetal blood vessels as well as the expression of the glucose transporters, Glut1 and Glut3, and the endothelial marker, CD34, were reduced in the placentas of CdCl2-treated male offspring compared to females. Interestingly, the placentas of females accumulated 80% more Cd than males after CdCl2 (5 mg/kg) administration. Female placentas also had higher concentrations of zinc and the zinc transporter Znt1 compared to males which may explain the limited changes in fetal growth observed following CdCl2 treatment. Taken together, disruption of vasculature development and reduced expression of glucose transporters in the placenta provide potential mechanisms underlying reduced fetal growth in male offspring despite the greater accumulation of Cd in female placentas.

Effects of Gestational Arsenic Exposures on Placental and Fetal Development in Mice: The Role of Cyr61 m6A

BACKGROUND

Several epidemiological investigations demonstrated that maternal arsenic (As) exposure elevated risk of fetal growth restriction (FGR), but the mechanism remains unclear.

OBJECTIVES

This study aimed to investigate the effects of gestational As exposure on placental and fetal development and its underlying mechanism.

METHODS

Dams were exposed to 0.15, 1.5, and 15 mg / L NaAsO 2 throughout pregnancy via drinking water. Sizes of fetuses and placentas, placental histopathology, and glycogen content were measured. Placental RNA sequencing was conducted. Human trophoblasts were exposed to NaAsO 2 (2 μ M ) to establish an in vitro model of As exposure. The mRNA stability and protein level of genes identified through RNA sequencing were measured. N 6 -Methyladenosine (m 6 A ) modification was detected by methylated RNA immunoprecipitation-quantitative real-time polymerase chain reason (qPCR). The binding ability of insulin-like growth factor 2 binding protein 2 to the gene of interest was detected by RNA-binding protein immunoprecipitation-qPCR. Intracellular S-adenosylmethionine (SAM) and methyltransferase activity were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and colorimetry, respectively. In vitro As + 3 methyltransferase (As3MT) knockdown or SAM supplementation and in vivo folic acid (FA) supplementation were used to evaluate the protective effect. A case-control study verified the findings.

RESULTS

Sizes of fetuses (exposed to 1.5 and 15 mg / L NaAsO 2 ) and placentas (exposed to 15 mg / L NaAsO 2 ) were lower in As-exposed mice. More glycogen + trophoblasts accumulated and the expression of markers of interstitial invasion was lower in the 15 mg / L NaAsO 2 -exposed mouse group in comparison with control. Placental RNA sequencing identified cysteine-rich angiogenic inducer 61 (Cyr61) as a candidate gene of interest. Mechanistically, mice and cells exposed to As had lower protein expression of CYR61, and this was attributed to a lower incidence of Cyr61 m 6 A . Furthermore, cells exposed to As had lower methyltransferase activity, suggesting that this could be the mechanism by which Cyr61 m 6 A was affected. Depletion of intracellular SAM, a cofactor for m 6 A methyltransferase catalytic domain, partially contributed to As-induced methyltransferase activity reduction. Either As3MT knockdown or SAM supplementation attenuated As-induced Cyr61 m 6 A down-regulation. In mice, FA supplementation rescued As-induced defective trophoblastic invasion and FGR. In humans, a negative correlation between maternal urinary As and plasma CYR61 was observed in infants who were small for gestational age.

DISCUSSION

Using in vitro and in vivo models, we found that intracellular SAM depletion-mediated Cyr61 m 6 A down-regulation partially contributed to As-induced defective trophoblastic invasion and FGR. https://doi.org/10.1289/EHP12207.

Association between female circulating heavy metal concentration and abortion: a systematic review and meta-analysis

Objective

This study aimed to evaluate the association between blood heavy metal (zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd)) concentrations and spontaneous abortion (SA) and recurrent pregnancy loss (RPL) and explore the possible endocrine dysfunction associated with it.

Methods

A literature search was performed in the PubMed, Embase, Cochrane Library, and Web of Science databases up to April 2023. The overall effects were expressed as the standard mean difference (SMD). Subgroup analysis was performed according to the type of abortion (SA or RPL). Stata 16.0 was utilized for data analysis.

Results

Based on the integrated findings, abortion women showed significantly lower Zn (SMD = -1.05, 95% CI: -1.74 to -0.36, p = 0.003) and Cu concentrations (SMD = -1.42, 95% CI: -1.97 to -0.87, p <0.001) and higher Pb (SMD = 1.47, 95% CI: 0.89-2.05, p <0.001) and Cd concentrations (SMD = 1.15, 95% CI: 0.45-1.85, p = 0.001) than normal pregnant women. Subgroup analysis showed that Zn and Cu deficiency and Cd and Pb exposure were significantly (p <0.05) associated with RPL, whereas Cu deficiency and Cd and Pb exposure were significantly (p <0.05) associated with SA.

Conclusion

Zn and Cu deficiencies and Pb and Cd exposure were associated with abortion. Endocrine dysfunction, such as insulin resistance, vitamin D insufficiency, and abnormal thyroid and sex hormone concentrations, is thought to be involved in heavy metal-related abortion.

Zinc alleviates cadmium-induced reproductive toxicity via regulating ion homeostasis, metallothionein expression, and inhibiting mitochondria-mediated apoptosis in the freshwater crab Sinopotamon henanense

Cadmium (Cd) is a carcinogenic environmental pollutant that harms male reproductive systems by lowering sperm quality, impairing spermatogenesis, and causing apoptosis. Although zinc (Zn) has been reported to alleviate Cd toxicity, the underlying mechanisms have not been fully elucidated. The aim of this work was to investigate the mitigating effects of Zn on Cd-induced male reproductive toxicity in the freshwater crab Sinopotamon henanense. Cd exposure not only resulted in its accumulation but also in Zn deficiency, decreased sperm survival rate, poor sperm quality, altered ultrastructure, and increased apoptosis in the testis of the crabs. Morever, Cd exposure increased the expression and distribution of metallothionein (MT) in the testis. However, Zn supplementation effectively mitigated the aforementioned effects of Cd, as demonstrated by preventing Cd accumulation, increasing Zn bioavailability, alleviating apoptosis, increasing mitochondrial membrane potential, decreasing reactive oxygen species (ROS) levels, and restoring MT distribution. Moreover, Zn also significantly reduced the expression of apoptosis-related (p53, Bax, CytC, Apaf-1, Caspase-9, Caspase-3), metal transporter-related ZnT1, metal-responsive transcription factor 1 (MTF1), and the gene and protein expression of MT, while increasing the expression of ZIP1 and Bcl-2 in the testis of Cd-treated crabs. In conclusion, Zn alleviates Cd-induced reproductive toxicity via regulating ion homeostasis, MT expression, and inhibiting mitochondria-mediated apoptosis in the testis of S. henanense. The information obtained in this study may serve as the foundation for further investigation into the development of mitigation strategies for adverse ecological and human health outcomes associated with Cd contamination or poisoning.

Activation of Atg5-dependent placental lipophagy ameliorates cadmium-induced fetal growth restriction

Cadmium (Cd), an environmental contaminant, can result in placental non-selective autophagy activation and fetal growth restriction (FGR). However, the role of placental lipophagy, a selective autophagy, in Cd-induced FGR is unclear. This work uses case-control study, animal experiments and cultures of primary human placental trophoblast cells to explore the role of placental lipophagy in Cd-induced FGR. We found association of placental lipophagy and all-cause FGR. Meanwhile, pregnancy Cd exposure induced FGR and placental lipophgay. Inhibition of placental lipophagy by pharmacological and genetic means (Atg5^-/- mice) exacerbated Cd-caused FGR. Inversely, activating of placental lipophagy relieved Cd-stimulated FGR. Subsequently, we found that activation of Atg5-dependent lipophagy degrades lipid droplets to produce free cholesterol, and promotes placental progesterone (P4) synthesis. Gestational P4 supplementation significantly reversed Cd-induced FGR. Altogether, activation of Atg5-dependent placental lipophagy ameliorates Cd-induced FGR.

Long-term cadmium exposure induces chronic obstructive pulmonary disease-like lung lesions in a mouse model

Accumulating evidences demonstrate that long-term exposure to atmospheric fine particles and air pollutants elevates the risk of chronic obstructive pulmonary disease (COPD). Cadmium (Cd) is one of the important toxic substances in atmospheric fine particles and air pollutants. In this study, we aimed to establish a mouse model to evaluate whether respiratory Cd exposure induces COPD-like lung injury. Adult male C57BL/6 mice were exposed to CdCl₂ (10 mg/L, 4 h per day) by inhaling aerosol for either 10 weeks (short-term) or 6 months (long-term). The mean serum Cd concentration was 6.26 μg/L in Cd-exposed mice. Lung weight and coefficient were elevated in long-term Cd-exposed mice. Pathological scores and alveolar destructive indices were increased in long-term Cd-exposed mouse lungs. Mean linear intercept and airway wall thickness were accordingly elevated in Cd-exposed mice. Inflammatory cell infiltration was obvious and inflammatory cytokines, including TNF-α, IL-1β, IL-6, IL-8, IL-10 and TGF-β, were up-regulated in Cd-exposed mouse lungs. α-SMA, N-cadherin and vimentin, epithelial-mesenchymal transition markers, and extracellular matrix collagen deposition around small airway, determined by Masson's trichrome staining, were shown in Cd-exposed mouse lungs. COPD-characteristic lung function decline was observed in long-term Cd-exposed mice. These outcomes show that long-term respiratory exposure to Cd induces COPD-like lung lesions for the first time.

Cadmium exposure during puberty damages testicular development and spermatogenesis via ferroptosis caused by intracellular iron overload and oxidative stress in mice

Cadmium (Cd) is a widespread environmental pollutant and a reproductive toxicant. It has been proved that Cd can reduce male fertility, however, the molecular mechanisms remain unveiled. This study aims to explore the effects and mechanisms of pubertal Cd exposure on testicular development and spermatogenesis. The results showed that Cd exposure during puberty could cause pathological damage to testes and reduce sperm counts in mice in adulthood. Moreover, Cd exposure during puberty reduced GSH content, induced iron overload and ROS production in testes, suggesting that Cd exposure during puberty may induce testicular ferroptosis. The results in vitro experiments further strengthened that Cd caused iron overload and oxidative stress, and decreased MMP in GC-1 spg cells. In addition, Cd disturbed intracellular iron homeostasis and peroxidation signal pathway based on transcriptomics analysis. Interestingly, these changes induced by Cd could be partially suppressed by pretreated with ferroptotic inhibitors, Ferrostatin-1 and Deferoxamine mesylate. In conclusion, the study demonstrated that Cd exposure during puberty maybe disrupted intracellular iron metabolism and peroxidation signal pathway, triggered ferroptosis in spermatogonia, and ultimately damaged testicular development and spermatogenesis in mice in adulthood.

Gestational cadmium exposure disrupts fetal liver development via repressing estrogen biosynthesis in placental trophoblasts

Cadmium (Cd), commonly found in diet and drinking water, is known to be harmful to the human liver. Nevertheless, the effects and mechanisms of gestational Cd exposure on fetal liver development remain unclear. Here, we reported that gestational Cd (150 mg/L) exposure obviously downregulated the expression of critical proteins including PCNA, Ki67 and VEGF-A in proliferation and angiogenesis in fetal livers, and lowered the estradiol concentration in fetal livers and placentae. Maternal estradiol supplement alleviated aforesaid impairments in fetal livers. Our data showed that the levels of pivotal estrogen synthases, such as CYP17A1 and 17β-HSD, was markedly decreased in Cd-stimulated placentae but not fetal livers. Ground on ovariectomy (OVX), we found that maternal ovarian-derived estradiol had no major effects on Cd-impaired development in fetal liver. In addition, Cd exposure activated placental PERK signaling, and inhibited PERK activity could up-regulated the expressions of CYP17A1 and 17β-HSD in placental trophoblasts. Collectively, gestational Cd exposure inhibited placenta-derived estrogen synthesis via activating PERK signaling, and therefore impaired fetal liver development. This study suggests a protective role for placenta-derived estradiol in fetal liver dysplasia shaped by toxicants, and provides a theoretical basis for toxicants to impede fetal liver development by disrupting the placenta-fetal-liver axis.

Early-life cadmium exposure elevates susceptibility to allergic asthma in ovalbumin-sensitized and challenged mice

Increasing evidence have demonstrated that early-life exposure to environmental toxicants elevates risk of allergic asthma. Cadmium (Cd) is widely present in the environment. The purposes of this study were to evaluate the impact of early-life Cd exposure on susceptibility to ovalbumin (OVA)-evoked allergic asthma. Newly weaned mice were subjected to a low concentration of CdCl₂ (1 mg/L) by drinking water for 5 consecutive weeks. Penh value, an index of airway obstruction, was increased in OVA-stimulated and challenged pups. Abundant inflammatory cells were observed in the lung of OVA-exposed pups. Goblet cell hyperplasia and mucus secretion were shown in the airway of OVA-stimulated and challenged pups. Early-life Cd exposure exacerbated OVA-evoked airway hyperreactivity, Goblet cell hyperplasia and mucus secretion. The in vitro experiments showed that mucoprotein gene MUC5AC mRNA was upregulated in Cd-exposed bronchial epithelial cells. Mechanistically, endoplasmic reticulum (ER) stress-related molecules GRP78, p-eIF2α, CHOP, p-IRE1α and spliced XBP-1 (sXBP-1) were elevated in Cd-subjected bronchial epithelial cells. The blockade of ER stress, using chemical inhibitor 4-PBA or sXBP-1 siRNA interference, attenuated Cd-induced MUC5AC upregulation in bronchial epithelial cells. These results indicate that early-life Cd exposure aggravates OVA-induced allergic asthma partially through inducing ER stress in bronchial epithelial cells.

Cholic acid exposure during late pregnancy causes placental dysfunction and fetal growth restriction by reactive oxygen species-mediated activation of placental GCN2/eIF2α pathway

Epidemiological studies suggest that fetal growth restriction (FGR) caused by gestational cholestasis is associated with elevated serum cholic acid (CA). Here, we explore the mechanism by which CA induces FGR. Pregnant mice except controls were orally administered with CA daily from gestational day 13 (GD13) to GD17. Results found that CA exposure decreased fetal weight and crown-rump length, and increased the incidence of FGR in a dose-dependent manner. Furthermore, CA caused placental glucocorticoid (GC) barrier dysfunction via down-regulating the protein but not the mRNA level of placental 11β-Hydroxysteroid dehydrogenase-2 (11β-HSD2). Additionally, CA activated placental GCN2/eIF2α pathway. GCN2iB, an inhibitor of GCN2, significantly inhibited CA-induced down-regulation of 11β-HSD2 protein. We further found that CA caused excessive reactive oxygen species (ROS) production and oxidative stress in mouse placentas and human trophoblasts. NAC significantly rescued CA-induced placental barrier dysfunction by inhibiting activation of GCN2/eIF2α pathway and subsequent down-regulation of 11β-HSD2 protein in placental trophoblasts. Importantly, NAC rescued CA-induced FGR in mice. Overall, our results suggest that CA exposure during late pregnancy induces placental GC barrier dysfunction and subsequent FGR may be via ROS-mediated placental GCN2/eIF2α activation. This study provides valuable insight for understanding the mechanism of cholestasis-induced placental dysfunction and subsequent FGR.

Perinatal exposure to glyphosate-based herbicides impairs progeny health and placental angiogenesis by disturbing mitochondrial function

Glyphosate-based herbicides (GBHs) are the most widely used pesticide worldwide and can provoke placental injury. However, whether and how GBHs damage angiogenesis in the placenta is not yet known. This work evaluated the safety of glyphosate on pregnant sows based on the limit level by governments and investigated the effects and mechanism of Low-GBHs (20 mg/kg) and High-GBHs (100 mg/kg) exposure on placental angiogenesis. Results showed that gestational exposure to GBHs decreased placental vessel density and cell multiplication by interfering with the expression of VEGFA, PLGF, VEGFr2 and Hand2 (indicators of angiogenesis), which may be in relation to oxidative stress-induced disorders of mitochondrial fission and fusion as well as the impaired function of the mitochondrial respiratory chain. Additionally, GBHs destroyed barrier function and nutrient transport in the placenta, and was accompanied by jejunum oxidative stress in newborn piglets. However, GBHs exposure had no significant differences on sow reproductive performance. As a natural antioxidant, betaine treatment protected placenta and newborn piglets against GBHs-induced damage. In conclusion, GBHs impaired placental angiogenesis and function and further damaged the health of postnatal progeny, these effects may be linked to mitochondrial dysfunction. Betaine treatment following glyphosate exposure provided modest relief.

Maternal exposure to metal mixtures during early pregnancy and fetal growth in the Jiangsu Birth Cohort, China

Previous epidemiological studies have reported that prenatal exposure to metals might have influence on fetal growth. Most studies assessed the effect of individual metals, while the investigation on the relationship between multiple metal exposure and fetal growth is sparse. The objective of the present study is to assess the joint impact of metal mixtures on fetal growth during pregnancy. A total of 1275 maternal-infant pairs from the Jiangsu Birth Cohort (JBC) Study were included to investigate the effect of maternal metal exposure on fetal biometry measures at 22-24, 30-32, and 34-36 weeks of gestation. Lead (Pb), arsenic (As), cadmium (Cd), mercury (Hg), chromium (Cr), vanadium(V), thallium (Tl) and barium (Ba) were measured by inductively coupled plasma mass spectrometry (ICP-MS) in maternal urine samples collected in the first trimester. We used general linear models and restricted cubic splines to test dose-response relationships between single metals and fetal growth. The weighted quantile sum (WQS) models were then applied to evaluate the overall effect of all these metals. We observed inverse associations of exposure to Pb, V and Cr with estimated fetal weight (EFW) at 34-36 weeks of gestation. Notably, maternal exposure to metal mixtures was significantly associated with reduced EFW at 34-36 weeks of gestation after adjusting for some covariates and confounders (aβ -0.05 [95% CI: 0.09, -0.01], P = 0.023), and this association was mainly driven by Cr (30.41%), Pb (23.92%), and Tl (15.60%). These findings indicated that prenatal exposure to metal mixtures might impose adverse effects on fetal growth.

Combination of high-fat diet and cadmium impairs testicular spermatogenesis in an m6A-YTHDF2-dependent manner

Environmental cadmium (Cd) or high-fat diet (HFD) exposure alone are risk factors of male infertility. However, the effect and mechanism of co-exposure to HFD and Cd on sperm quality remain unclear. This study was aimed to explore the combined effects of HFD and Cd on spermatogenesis as well as its m6A-dependent mechanism in vivo and in vitro. As a result, co-exposure of HFD and Cd resulted in a significant decrease in the number of mature testicular seminiferous tubules and epididymis sperm quantity in mice, compared with Cd or HFD exposure alone. Correspondingly, the mRNAs expression of Smc3(spermatocytes marker), Acrv1(round spermatids marker) and Lzumo3(elongated spermatids marker) were downregulated in HFD and Cd group. Furthermore, combined exposure downregulated the expression of meiosis-related proteins (STRA8 and SYCP3), increased the m6A level of Stra8, and upregulated the expression of m6A-related proteins (METTL3 and YTHDF2) in mouse spermatocytes. Mechanistically, the above-mentioned impacts caused by co-exposure were markedly restored by Mettl3 siR and Ythdf2 siR. In addition, RNA stability assay showed that Ythdf2 siR obviously reversed co-exposure-increased Stra8 mRNA degradation rate in actinomycin-D-treated mouse spermatocytes. Meanwhile, excess ROS was observed in combined-exposure group, and a free radical scavenger N-tert-Butyl-α-phenylnitrone (PBN) attenuated co-exposure-upregulated expression of METTL3 and YTHDF2 in mouse spermatocytes. These results suggested that combination of HFD and Cd impaired spermatogenesis by degrading Stra8 in an m6A-YTHDF2-dependent manner via ROS activation.

Environmental cadmium exposure during gestation impairs fetal brain and cognitive function of adult offspring via reducing placenta-derived E2 level

Early-life exposure to environmental cadmium (Cd) is known to cause developmental disorders, yet the effect and mechanism of gestational exposure to Cd on the offspring's cognitive function remains unclear. Placenta as a well-established target organ for Cd-impaired fetal development, its role in estrogen regulation and offspring cognitive function is unknown. Our in vivo experiments found that gestational Cd exposure impaired cognitive function in adult male offspring, accompanied with lowered 17β-estradiol (E2) level in the male fetal brain upon Cd exposure. Correspondingly, the expression of synapse-associated proteins including brain-derived neurotrophic factor (BDNF), post-synaptic density protein 95 (PSD95) and synapsin-1 were downregulated, which were reversed when supplemented with E2 hormone during gestation. Further observation showed placental estrogen synthesis inhibition and general control non-derepressible 2 (GCN2) signaling activation upon Cd exposure, whereas placental estrogen synthesis could be restored through inhibiting GCN2 activity. Based on ovariectomy (OVX) of pregnant mice, we confirmed that Cd exposure reduced E2 level in fetal brain via inhibiting placenta-derived estrogen synthesis. The aforementioned Cd-induced fetal brain injury and cognitive impairment in adult offspring were significantly alleviated when pregnant dams were supplemented with anti-stress agent N-Acetyl-l-cysteine. In summary, Cd disrupted placenta-derived estrogen synthesis via activating GCN2 signaling, and thereby caused cognitive impairment in adult offspring mice. Our findings suggest that placenta-derived estrogen may be an effect marker of environmental toxicants-evoked cognitive dysfunction in adult offspring and suggest that environmental toxicants may affect the fetal brain development via placenta-fetal-brain axis.

Mitochondrial ROS-mediated ribosome stalling and GCN2 activation are partially involved in 1-nitropyrene-induced steroidogenic inhibition in testes

In the past 50 years, testosterone (T) level in men has declined gradually. In this research, we discovered that acute exposure to 1-nitropyrene (1-NP), an environmental stressor from polluted atmosphere, reduced T contents by downregulating steroidogenic proteins in mouse testes and Leydig cells. Acute 1-NP exposure caused GCN2 activation and eIF2α phosphorylation, a marker of integrated stress, in mouse testes and Leydig cells. GCN2iB, a selective GCN2 kinase inhibitor, and siGCN2, the GCN2-targeted short interfering RNA, attenuated 1-NP-induced reduction of steroidogenic proteins in Leydig cells. Mechanistically, mitochondrial membrane potential was reduced and ATP5A, UQCRC2, SDHB and NDUFB8, four OXPHOS subunits, were reduced in 1-NP-exposed Leydig cells. Cellular mitochondrial respiration was inhibited and ATP production was reduced. Moreover, mitochondrial reactive oxygen species (ROS) were elevated in 1-NP-exposed Leydig cells. The interaction between GCN2 and uL10, a marker of ribosome stalling, was observed in 1-NP-exposed Leydig cells. MitoQ, a mitochondria-targeted antioxidant, attenuated1-NP-evoked ATP depletion and ribosome stalling in Leydig cells. Moreover, MitoQ suppressed 1-NP-caused GCN2 activation and eIF2α phosphorylation in Leydig cells. In addition, MitoQ alleviated 1-NP-induced steroidogenic inhibition in mouse testes. In conclusion, mitochondrial ROS-mediated ribosome stalling and GCN2 activation are partially involved in environmental stress-induced steroidogenic inhibition in testes.

Human placenta mesenchymal stem cell-derived exosome shuttling microRNA-130b-3p from gestational diabetes mellitus patients targets ICAM-1 and perturbs human umbilical vein endothelial cell angiogenesis

OBJECTIVE

The aim of this study was to investigate the roles of miR-130b-3p and ICAM-1 in gestational diabetes mellitus (GDM) and their potential association.

METHODS

Human placenta mesenchymal stem cells (PlaMSCs) were isolated from GDM patients, and the effects of the PlaMSCs from GDM patients (GDM-MSCs) and the exosomes secreted by GDM-MSCs on human umbilical vein endothelial cell (HUVEC) proliferation, migration, and angiogenesis were detected. Next, GDM-MSCs were transfected with miR-130b-3p antagomir to modify miR-130b-3p expression in GDM-MSCs-derived exosomes, and the exosomes with modified miR-130b-3p expression were cultured with HUVECs to evaluate exosomal miR-130b-3p on HUVEC function. Furthermore, a target gene of miR-130b-3p was predicted and assessed. The miR-130b-3p-modified exosomes were cultured with HUVECs transfected with ICAM-1 shRNA to determine the effect of miR-130b-3p-ICAM-1 crosstalk on HUVEC function. Additionally, a GDM mouse model was conducted to further study the effect of miR-130b-3p in GDM in vivo.

RESULTS

GDM-MSCs inhibited HUVEC proliferation and angiogenesis. The elevated expression of miR-130b-3p was found in GDM-MSCs-derived exosomes. GDM-MSCs-derived exosomes repressed the proliferation and angiogenesis of HUVECs and miR-130b-3p inhibition could restrain the inhibition of the exosomes on HUVEC function. Mechanistically, miR-130b-3p downregulated ICAM-1 expression in a targeted manner, and thereby enhanced HUVEC proliferation, migration, and angiogenesis and increased the expression of angiogenesis-related factors. Moreover, miR-130b-3p inhibition promoted placental angiogenesis in GDM mice and upregulated ICAM-1 expression.

CONCLUSION

Conclusively, GDM-MSCs-derived exosomes shuttling miR-130b-3p repressed proliferation, migration, and angiogenesis of HUVECs by regulating ICAM-1 expression.

Effects of the maternal gut microbiome and gut-placental axis on melatonin efficacy in alleviating cadmium-induced fetal growth restriction

Cadmium (Cd) is a major environmental stressor that induces fetal growth restriction (FGR). Also, changes in gut microbiome diversity-which can be modulated positively by melatonin (Mel) have implications on fetal development and placental functions. Therefore, this study aimed to explore whether the role of Mel in counteracting the Cd-induced FGR by regulating placental barrier injury, endoplasmic reticulum stress (ERS) and mitophagy in pregnant mice is mediated-in part- via the gut microbiota modulations. Pregnant mice were intraperitoneally injected with CdCl₂ (5 mg/kg) and Mel (5 mg/kg) once daily, respectively, at the same time from gestational day (GD) 8 to GD18, and then the maternal colon and placental tissues were collected for detection. To investigate the inner relationship between intestinal flora and the protection of Mel on FGR caused by Cd, gut microbiota transplantation (GMT) was carried out from GD0 to GD18 after the removal of intestinal microbiota by antibiotics. Results indicated that Mel relieved barrier injury, ERS and mitophagy in the placenta, and reversed the maternal gut microbiota dysbiosis. The GMT approach suggested a role of intestinal microbiota in placental barrier injury, ERS and mitophagy induced by Cd. Overall, the results highlighted that the intestinal microbiota and gut-placental axis play a central role in the protective effect of Mel against Cd-induced FGR.

Prenatal exposure to triphenyl phosphate activated PPARγ in placental trophoblasts and impaired pregnancy outcomes

The health risks of triphenyl phosphate (TPhP) have increased since its widespread application. Using placental trophoblast cell line JEG-3, we demonstrated that TPhP could induce endoplasmic reticulum stress (ERS) and cell apoptosis through PPARγ-mediated lipid metabolism. However, the developmental toxicity of TPhP through the placenta is not known. In this study, prenatal TPhP exposure to mice was investigated. Pregnant mice were orally exposed to TPhP (1 and 5 mg/kg) from embryonic day 0 (E0) until delivery. The results showed that TPhP could accumulate in placenta and impair pregnancy outcomes. After exposure, at E18, placental hormone chorionic gonadotrophin and testosterone levels were significantly decreased, but progesterone and estradiol levels were significantly increased, and placental angiogenesis was activated in the low-dose exposure group. While, in the high-dose exposure group, only estradiol levels were significantly increased. Different with the effect on hormone level or angiogenesis, TPhP significantly increased PPARγ and its regulated lipid transport proteins FABP, FATP, and CD36, and induced lipid accumulation in placental trophoblasts of both low- and high-exposure group. RNA-seq analysis of the placenta identified differentially expressed genes that were mainly involved in the ERS and MAPK signaling pathways. Western blot analysis verified that the protein levels related to ERS stress and apoptosis were significantly increased. To further confirm the role of PPARγ in TPhP mediated placental toxicity, pregnant mice were orally exposed to TPhP (1 mg/kg) or TPhP (1 mg/kg) + GW9662 (PPARγ inhibitor, 2 mg/kg) from E0 until delivery. The results showed that GW9662 could ameliorate the effect of TPhP on placental lipid accumulation, ERS and cell apoptosis, suggesting that PPARγ mediated the placental toxicity of TPhP. Overall, our results indicated that prenatal TPhP exposure impaired pregnancy outcomes, at least partly through PPARγ regulated function of trophoblast.

Identification of StAP2/ERF genes of potato (Solanum tuberosum) and their multiple functions in detoxification and accumulation of cadmium in yest: Implication for Genetic-based phytoremediation

The discovery of genes responsible for the tolerance to heavy metals is critical for genome-based phytotechnologies. In this study, we exposed potato (Solanum tuberosum L.) to Cd/Pb/Zn/Ni/Cu as an approach to explore the potential genes associated with stress tolerance. Using genome-wide analysis, we identified 181 potential StAP2/ERF genes that were classified into three subgroups. These StAP2/ERF genes were significantly related to heavy metal stress and are more specifically related to Cd tolerance in yeast. Yeast complementation tests showed that the StAP2/ERF129/139 genes (Subgroup 1) decreased Cd accumulation (Cd reduction-type), whilst the StAP2/ERF044/180 genes (Subgroup 2) promoted Cd accumulation in yeast which showed inhibited growth (Cd accumulation-type). The StAP2/ERF075/077/126 genes (Subgroup 3) promoted Cd accumulation and yeast growth (Cd detoxification-type). We used phylogenetic analysis to classify the 181 genes into three Cd tolerant types defined above in which the numbers of Cd reduction, accumulation, and detoxification type genes were 81, 65 and 35 respectively. Also, we performed tandem duplication, phylogenetic, and conserved motifs analysis to characterization the StAP2/ERF genes and results supported their functions in Cd tolerance. Our study showed that StAP2/ERFs is indispensable in Cd uptake and tolerance, and may be useful towards designing gene-modified plants with improved Cd tolerances.

Gestational exposure to environmental cadmium induces placental apoptosis and fetal growth restriction via Parkin-modulated MCL-1 degradation

Heavy metal cadmium (Cd), a classical environmental pollutant, causes placental apoptosis and fetal growth restriction (FGR), whereby the mechanism remains unclear. Here, our human case-control study firstly showed that there was a positive association of Parkin mitochondrial translocation, MCL-1 reduction, placental apoptosis, and all-cause FGR. Subsequently, Cd was administered to establish in vitro and in vivo models of placental apoptosis or FGR. Our models demonstrated that Parkin mitochondrial translocation was observed in Cd-administrated placental trophoblasts. Meaningfully, Parkin siRNA (siR) dramatically mitigated Cd-triggered apoptosis in placental trophoblasts. Mdivi-1 (M-1), an inhibitor for Parkin mitochondrial translocation, mitigated Cd-induced apoptosis in placental trophoblasts, which further ameliorated the effect of attenuated placental sizes in Cd-exposed mice. Furthermore, the interaction of MCL-1 with Parkin or Ub in Cd-stimulated cells was stronger than that in controls. MG132, an inhibitor for proteasome, abolished MCL-1 degradation in Cd-stimulated cells. Importantly, Parkin siR and M-1 memorably abolished the ubiquitin-dependent degradation of MCL-1 in placental trophoblasts. Interestingly, mito-TEMPO and melatonin, two mitochondria-targeted antioxidants, obviously rescued Cd-caused mitochondrial membrane potential (MMP) decrease, Parkin mitochondrial translocation, MCL-1 degradation, and apoptosis in placental trophoblasts. In conclusion, cadmium induces placental apoptosis and FGR via mtROS-mediated Parkin-modulated degradation of MCL-1.

miR-6769b-5p targets CCND-1 to regulate proliferation in cadmium-treated placental trophoblasts: Association with the impairment of fetal growth

Environmental cadmium (Cd) is positively associated with placental impairment and fetal growth retardation. Nevertheless, its potential mechanisms remain unclear. microRNAs (miRNAs) are known to influence placental development and fetal growth. This work was aimed to determine which miRNAs are involved in Cd-impaired placental and fetal development based on the mRNA and miRNA expression profiles analysis. As a result, gestational Cd exposure deceased fetal and placental weight, and reduced the protein level of PCNA in human and mouse placentae. Furthermore, the results of mRNA microarray showed that Cd-downregulated mRNAs were predictively correlated with several biological processes, including cell proliferation, differentiation and motility. In addition, the results of miRNA microarray and qPCR assay demonstrated that Cd significantly increased the level of miR-6769b-5p, miR-146b-5p and miR-452-5p. Integrated analysis of Cd-upregulated miRNAs predicted target genes and Cd-downregulated mRNAs found that overlapping mRNAs, such as CCND1, CDK13, RINT1 and CDC26 were also significantly associated with cell proliferation. Further experiments showed that miR-6769b-5p inhibitor, but not miR-146b-5p and miR-452-5p, markedly reversed Cd-downregulated the expression of proliferation-related mRNAs, and thereby restored Cd-decreased the proteins level of CCND1 and PCNA in human placental trophoblasts. Dual luciferase reporter assay further revealed that miR-6769b-5p directly targets CCND1. Finally, the case-control study demonstrated that increased miR-6769b-5p level and impaired cell proliferation were observed in small-for-gestational-age human placentae. In conclusion, miR-6769b-5p targets CCND-1 to regulate proliferation in Cd-treated placental trophoblasts, which is associated with the impairment of fetal growth. Our findings imply that placental miR-6769b-5p may be used as an epigenetic marker for environmental pollutants-caused fetal growth restriction and its late-onset chronic diseases.

The Impact of Oxidative Stress of Environmental Origin on the Onset of Placental Diseases

Oxidative stress (OS) plays a pivotal role in placental development; however, abnormal loads in oxidative stress molecules may overwhelm the placental defense mechanisms and cause pathological situations. The environment in which the mother evolves triggers an exposure of the placental tissue to chemical, physical, and biological agents of OS, with potential pathological consequences. Here we shortly review the physiological and developmental functions of OS in the placenta, and present a series of environmental pollutants inducing placental oxidative stress, for which some insights regarding the underlying mechanisms have been proposed, leading to a recapitulation of the noxious effects of OS of environmental origin upon the human placenta.

Paternal exposure to microcystin-LR induces fetal growth restriction partially through inhibiting cell proliferation and vascular development in placental labyrinth

Microcystin-leucine arginine (MC-LR) has reproductive and developmental toxicities. Previous studies indicated that gestational exposure to MC-LR induced fetal growth restriction in mice. The aim of this study was to further evaluate the effect of paternal MC-LR exposure before mating on fetal development. Male mice were intraperitoneally injected with either normal saline or MC-LR (10 μg/kg) daily for 35 days. Male mouse was then mated with female mice with 1:1 ratio. There was no significant difference on the rates of mating and pregnancy between MC-LR-exposed male mice and controls. Body weight and crown-rump length were reduced in fetuses whose fathers were exposed to MC-LR. Despite no difference on relative thickness of labyrinthine layer, cell proliferation, as measured by Ki67 immunostaining, was reduced in labyrinth layer of MC-LR-exposed mice. Moreover, blood sinusoid area in labyrinth layer was decreased in the fetus whose father was exposed to MC-LR before mating. Correspondingly, cross-sectional area of CD34-positive blood vessel in labyrinth layer was lower in fetuses whose fathers were exposed to MC-LR than in controls. These results provide evidence that paternal MC-LR exposure before mating induces fetal growth restriction partially through inhibiting cell proliferation and vascular development in labyrinth layer.

Endoplasmic reticulum stress-mediated autophagy activation is involved in cadmium-induced ferroptosis of renal tubular epithelial cells

Acute cadmium (Cd) exposure is a significant risk factor for renal injury and lacks effective treatment strategies. Ferroptosis is a recently identified iron-dependent form of nonapoptotic cell death mediated by membrane damage resulting from lipid peroxidation, and it is implicated in many diseases. However, whether ferroptosis is involved in Cd-induced renal injury and, if so, how it operates. Here, we show that Cd can induce ferroptosis in kidney and renal tubular epithelial cells, as demonstrated by elevation of intracellular iron levels and lipid peroxidation, as well as impaired antioxidant production. Treatment with a ferroptosis inhibitor alleviated Cd-induced cell death. Intriguingly, we established that Cd-induced ferroptosis depended on endoplasmic reticulum (ER) stress, by demonstrating that Cd activated the PERK-eIF2α-ATF4-CHOP pathway and that inhibition of ER stress reduced ferroptosis caused by Cd. We further found that autophagy was required for Cd-induced ferroptosis because the inhibition of autophagy by chloroquine mitigated Cd-induced ferroptosis. Furthermore, we showed that iron dysregulation by ferritinophagy contributed to Cd-induced ferroptosis, by showing that the iron chelator desferrioxamine alleviated Cd-induced cell death and lipid peroxidation. In addition, ER stress is likely activated by MitoROS which trigger autophagy and ferroptosis. Collectively, our results indicate that ferroptosis is involved in Cd-induced renal toxicity and regulated by the MitoROS-ER stress-ferritinophagy axis.

Gestational cadmium exposure impairs placental angiogenesis via activating GC/GR signaling

Gestational exposure to environmental Cd caused placental angiogenesis impairment and fetal growth restriction (FGR). However, its mechanism remained unclear. This study was to investigate the effects of Cd exposure during pregnancy on placental angiogenesis and its mechanism. Pregnant mice were exposed to CdCl2 (4.5 mg/kg) on gestational day (GD) 8 with or without melatonin (MT) (5.0 mg/kg), an anti-endoplasmic reticulum stress agent, from GD7 to GD15. Human primary placental trophoblasts and JEG-3 cells were stimulated using CdCl2 (20 μM) after MT (1 mM) preprocessing. We firstly found MT treatment obviously mitigated environmental Cd-induced placental angiogenesis disorder and reduction of the VEGF-A level. Mechanistically, MT reversed environmental Cd-downregulated the protein expression of VEGF-A via inhibiting glucocorticoid receptor (GR) activation. Notably, our data showed MT treatment antagonized Cd-activated GC/GR signaling via blocking PERK signaling and thereby upregulated VEGF-A and 11β-HSD2 protein expression. Based upon the population case-control study, the levels of VEGF-A and 11β-HSD2 protein in small-for-gestational-age placentae were significantly reduced when compared to appropriate-for-gestational-age placentae. Overall, environmental Cd exposure during gestation impaired placental angiogenesis via PERK-regulated GC/GR signaling in placental trophoblasts. Our findings will provide a basis for prevention and treatment of placental impairments and fetal growth restriction caused by environment toxicants in future.

Microcystin-LR inhibits testosterone synthesis via reactive oxygen species-mediated GCN2/eIF2α pathway in mouse testes

Previous studies demonstrated that microcystin-leucine-arginine (MC-LR) disrupted testosterone (T) synthesis, but the underlying mechanisms are not entirely elucidated. This study aims to explore the role of reactive oxygen species (ROS)-mediated GCN2/eIF2α activation on MC-LR-induced disruption of testicular T synthesis. Male mice were intraperitoneally injected with MC-LR (0 or 20 μg/kg) daily for 5 weeks. Serum T was decreased in MC-LR-exposed mice (0.626 ± 0.122 vs 24.565 ± 8.486 ng/ml, P < 0.01), so did testicular T (0.667 ± 0.15 vs 8.317 ± 1.387 ng/mg protein, P < 0.01). Steroidogenic proteins including StAR, CYP11A1 and CYP17A1 were downregulated in MC-LR-exposed mouse testes and TM3 cells. Mechanistically, p-GCN2 and p-eIF2α were elevated in MC-LR-exposed TM3 cells. GCN2iB attenuated MC-LR-induced GCN2 and eIF2α phosphorylation in TM3 cells. Moreover, GCN2iB attenuated MC-LR-induced downregulation of steroidogenic proteins in TM3 cells. Further analysis found that cellular ROS were elevated and HO-1 was upregulated in MC-LR-exposed TM3 cells. PBN rescued MC-LR-induced activation of GCN2/eIF2α signaling in TM3 cells. Additionally, pretreatment with PBN attenuated MC-LR induced downregulation of steroidogenic proteins and synthases in TM3 cells. These results suggest that ROS-mediated GCN2/eIF2α activation contributes partially to MC-LR-caused downregulation of steroidogenic proteins and synthases. The present study provides a new clue for understanding the mechanism of MC-LR-induced endocrine disruption.